The monk seal, the most endangered pinniped worldwide and the only one found in the Mediterranean, has suffered a drastic decline in the last few decades. Nowadays molecular techniques allow to detect minute amounts of DNA released in the environment (eDNA) by any organism. We present three qPCR-assays targeting the monk seal mitogenome. The assays were soundly tested on an extensive/diversified sample set (n=73), including positive controls from Madeira breeding population and two opportunistic Mediterranean eDNA-sample collections (offshore/coastal) from on-going projects. Monk seal DNA was detected in 47.2% and 66.7% of the samples collected in the Tyrrhenian from a ferry platform (2018-2019) and in the Pelagie archipelago (2020) respectively, anticipating (up to 2 year) visual observations occurred subsequently in proximity of the sampled areas. In the Tyrrhenian, detection occurrence increased between 2018 and 2019. Monk seal DNA recoveries were commoner in night-time ferry-samples, suggesting nocturnal predatory activity in pelagic waters. The proposed technique provides a non-invasive and yet highly-sensitive tool for defining the monk seal actual range, its recovery rate and pinpoint coastal/offshore localities where prioritizing conservation.